Inert gases, such as nitrogen and rare gases, namely helium, neon, argon, krypton, xenon and their mixtures, are commonly employed in many industries, in particular the electronics industry. The latter industry very particularly requires the inert gases to be as pure as possible and in particular freed from their oxygen (O.sub.2) and carbon monoxide (CO) impurities.
Now, these inert gases, usually produced by cryogenic distillation, contain impurities of oxygen (O.sub.2) and/or carbon monoxide (CO) type, in proportions generally of greater than a few hundreds of ppb (parts per billion by volume).
Consequently, when it is desired to obtain an inert gas which is substantially free from its O.sub.2 and/or CO impurities, it is essential to subject this gas to a purification in order to remove the impurities.
Some processes for the purification of inert gases are known in the prior art.
Thus, U.S. Pat. No. 3,996,028 describes a process for the purification of argon by passing this argon through a synthetic zeolite of the type A which makes possible the adsorption of oxygen, the adsorption being carried out at a temperature of between -186.degree. C. and -133.degree. C.
U.S. Pat. No. 5,106,399 describes, for its part, a process for the purification of argon, in particular of liquid argon, which uses a molecular sieve, the oxygen, hydrogen and/or carbon monoxide impurities contained in the flow to be purified being adsorbed preferentially on a material composed of alumina/silica balls supporting a high percentage of nickel.
However, these various known processes exhibit many disadvantages. In particular, they do not make it possible to purify inert gases, such as nitrogen and rare gases, from at least one of their oxygen and carbon monoxide impurities to a level of the order of a ppb (part per billion by volume).
It is thus necessary to develop new processes which make it possible to arrive at such thresholds for the purification of the inert gases from their oxygen and/or carbon monoxide impurities.
Moreover, the known processes are limited from the viewpoint of the throughput of the inert gas to be purified, that is to say of the amount of the inert gas which can be purified during a given time period. Thus, the maximum throughput threshold achieved by the conventional processes generally lies in the region of a few hundreds of Sm.sup.3 /h.
It is thus necessary to develop processes which make it possible to obtain higher throughputs of substantially purified inert gases.
In addition, some known purification processes also exhibit the disadvantage of being employed at very low temperatures, often lower than -100.degree. C., which requires perfect thermal insulation of the purification device, in order to prevent any entry of heat, and thus generates a large increase in the production costs.
In order to minimize these production costs, it is thus desirable to design a process for the purification of inert gases which can be employed at a temperature greater than or equal to -40.degree. C. and which uses an efficient, commonplace and inexpensive adsorbent.